pkg/sensors: export BPF maps memlock to tracing policy lists

Retrieve memlock from each map loaded by a sensor.

Signed-off-by: Mahe Tardy <mahe.tardy@gmail.com>

pkg/sensors/collection.go

@@ -174,6 +174,7 @@ func (cm *collectionMap) listPolicies() []*tetragon.TracingPolicyStatus {
 
 		for _, sens := range col.sensors {
 			pol.Sensors = append(pol.Sensors, sens.GetName())
+			pol.KernelMemoryBytes += uint64(sens.TotalMemlock())
 		}
 
 		ret = append(ret, &pol)

pkg/sensors/delayed_sensor_test.go

@@ -31,6 +31,10 @@ type TestDelayedSensor struct {
 	ch     chan struct{}
 }
 
+func (tds TestDelayedSensor) TotalMemlock() int {
+	return 0
+}
+
 func (tds *TestDelayedSensor) GetName() string {
 	return tds.name
 }

pkg/sensors/sensors.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/cilium/tetragon/pkg/bpf"
 	"github.com/cilium/tetragon/pkg/logger"
 	"github.com/cilium/tetragon/pkg/policyfilter"
 	"github.com/cilium/tetragon/pkg/sensors/program"
@@ -75,6 +76,9 @@ type SensorIface interface {
 	Load(bpfDir string) error
 	Unload() error
 	Destroy()
+	// TotalMemlock is the total amount of memlock bytes for BPF maps used by
+	// the sensor's programs.
+	TotalMemlock() int
 }
 
 func (s *Sensor) GetName() string {
@@ -85,6 +89,23 @@ func (s *Sensor) IsLoaded() bool {
 	return s.Loaded
 }
 
+func (s Sensor) TotalMemlock() int {
+	uniqueMap := map[int]bpf.ExtendedMapInfo{}
+	for _, p := range s.Progs {
+		for id, info := range p.LoadedMapsInfo {
+			// we could first check that it exist then write but all maps with
+			// same ID on the kernel should share the same info
+			uniqueMap[id] = info
+		}
+	}
+
+	var total int
+	for _, info := range uniqueMap {
+		total += info.Memlock
+	}
+	return total
+}
+
 // SensorHook is the function signature for an optional function
 // that can be called during sensor unloading and removing.
 type SensorHook func() error